Repair Systems
Floor patching compounds
Polymer-modified feather-edge floor patching compound — technical reference for magnesite flooring deterioration in Australian remedial building practice. Covers system selection, product comparisons, and brand equivalents.
What is floor patching compounds?
Floor patching compounds are thin-section repair mortars used to fill localised depressions, spalled areas, saw-cut edges, and surface irregularities in magnesite or concrete substrates before a self-levelling compound or floor covering is applied. They are trowel-applied and can feather to a near-zero edge — unlike self-levelling compounds which have a minimum 2–3 mm application thickness. Commonly used as a pre-levelling repair step to address spot damage and high-to-low transitions too deep or too localised for SLU alone. Polymer-modified types offer improved adhesion and reduced shrinkage. Rapid-setting variants allow same-day progression to SLC application. Must be applied over a primed surface and must not be used to fill large-volume deficiencies where an SLU would be more appropriate.
Product Reference
Scroll right to see all brands. Use each card's TDS link for verified specifications before specifying on any project.
Sika MonoTop-412N
fine polymer repair mortar for feather edge to 10 mm, 25 kg bag
System Description
For localised failed areas, low spots, and surface irregularities in existing magnesite or concrete substrate. Prime surface first. Can feather to near-zero edge. Apply in layers not exceeding 10 mm per lift. Not a substitute for full self-levelling compound where planarity tolerance is critical for hard floor coverings.
Technical Properties
- Fine aggregate for cosmetic, thin-section, and profile repairs from 0 to 10 mm depth
- EN 1504-3 R3 structural-grade bond strength even in thin sections
- Can be feathered to near-zero at repair edges — ideal for blending into surrounding concrete
- Normal-setting time provides adequate workable window for trowel finishing
Limitations
- Not suitable for deep structural spalls — maximum 10 mm single layer; use MonoTop-352NFG for deeper sections
- Fine grade requires careful mix water control — excess water causes shrinkage cracking
- Colour matching to aged concrete requires sponge-float technique before cure — applicator skill dependent
PROCUREMENT SOURCES
Ardex Feather Finish
polymer-modified feather-edge skimming and patching compound, 10 kg bag
System Description
For localised failed areas, low spots, and surface irregularities in existing magnesite or concrete substrate. Prime surface first. Can feather to near-zero edge. Apply in layers not exceeding 10 mm per lift. Not a substitute for full self-levelling compound where planarity tolerance is critical for hard floor coverings.
Technical Properties
- Polymer-modified feather-edge compound — can be applied to near-zero thickness at repair edges
- Fine aggregate suitable for cosmetic profiling, surface fairing, and thin-section patching to 10 mm
- Part of the Ardex floor levelling system — compatible with Ardex P 51 primer and floor toppings
- Single-component — no specialist mixing equipment required
Limitations
- Not a structural repair mortar — do not specify where EN 1504-3 R3/R4 structural compliance is required
- Cosmetic application only — does not address sub-surface substrate condition
- Not suitable for trafficked surfaces without protective topping
PROCUREMENT SOURCES
Fosroc Renderoc FC
fine cosmetic fairing mortar for thin-section patching, 25 kg bag
System Description
For localised failed areas, low spots, and surface irregularities in existing magnesite or concrete substrate. Prime surface first. Can feather to near-zero edge. Apply in layers not exceeding 10 mm per lift. Not a substitute for full self-levelling compound where planarity tolerance is critical for hard floor coverings.
Technical Properties
- Fine cosmetic mortar for blowholes, form-face blemishes, and surface defects in architectural concrete
- Featherable to thin sections at edges — low visible repair line when correctly finished
- EN 1504-3 R2 compliance — meets minimum classification for cosmetic concrete repairs
- Low-shrinkage formulation reduces risk of cosmetic crack re-opening post-repair
Limitations
- EN 1504-3 R2 only — not suitable for structural repairs; use Renderoc HB for structural applications
- Cosmetic quality is heavily applicator-dependent — requires skilled concretor for acceptable finish
- Cannot address underlying substrate condition — cosmetic layer only
PROCUREMENT SOURCES
Mapei Planitop Fast 330
rapid-set repair mortar for thin-section floor patching, 25 kg bag
System Description
For localised failed areas, low spots, and surface irregularities in existing magnesite or concrete substrate. Prime surface first. Can feather to near-zero edge. Apply in layers not exceeding 10 mm per lift. Not a substitute for full self-levelling compound where planarity tolerance is critical for hard floor coverings.
Technical Properties
- Can be feathered to near-zero edge for localised transitions and surface irregularities
- Rapid-setting formulations allow same-day progression to self-levelling compound application
Limitations
- Not suitable for large-volume levelling — use self-levelling compound for areas exceeding 5 mm depth over large areas
- Requires surface priming — adhesion will fail on unprimed or contaminated substrates
PROCUREMENT SOURCES
Parchem Renderoc FC
polymer-modified fairing coat for floor patching, 25 kg bag
System Description
For localised failed areas, low spots, and surface irregularities in existing magnesite or concrete substrate. Prime surface first. Can feather to near-zero edge. Apply in layers not exceeding 10 mm per lift. Not a substitute for full self-levelling compound where planarity tolerance is critical for hard floor coverings.
Technical Properties
- Can be feathered to near-zero edge for localised transitions and surface irregularities
- Rapid-setting formulations allow same-day progression to self-levelling compound application
Limitations
- Not suitable for large-volume levelling — use self-levelling compound for areas exceeding 5 mm depth over large areas
- Requires surface priming — adhesion will fail on unprimed or contaminated substrates
PROCUREMENT SOURCES
System Description
Use for isolated floor depressions, damaged saw-cut edges, or localised substrate failure prior to self-levelling. Trafficable typically within 1–3 hours. Do not overcoat with SLC until mortar has reached sufficient compressive strength — check TDS.
Technical Properties
- Fine aggregate for cosmetic, thin-section, and profile repairs from 0 to 10 mm depth
- EN 1504-3 R3 structural-grade bond strength even in thin sections
- Can be feathered to near-zero at repair edges — ideal for blending into surrounding concrete
- Normal-setting time provides adequate workable window for trowel finishing
Limitations
- Not suitable for deep structural spalls — maximum 10 mm single layer; use MonoTop-352NFG for deeper sections
- Fine grade requires careful mix water control — excess water causes shrinkage cracking
- Colour matching to aged concrete requires sponge-float technique before cure — applicator skill dependent
PROCUREMENT SOURCES
System Description
Use for isolated floor depressions, damaged saw-cut edges, or localised substrate failure prior to self-levelling. Trafficable typically within 1–3 hours. Do not overcoat with SLC until mortar has reached sufficient compressive strength — check TDS.
Technical Properties
- Can be feathered to near-zero edge for localised transitions and surface irregularities
- Rapid-setting formulations allow same-day progression to self-levelling compound application
Limitations
- Not suitable for large-volume levelling — use self-levelling compound for areas exceeding 5 mm depth over large areas
- Requires surface priming — adhesion will fail on unprimed or contaminated substrates
PROCUREMENT SOURCES
Fosroc Renderoc LA
rapid low-alkali repair mortar for thin-section floor patching, 25 kg bag
System Description
Use for isolated floor depressions, damaged saw-cut edges, or localised substrate failure prior to self-levelling. Trafficable typically within 1–3 hours. Do not overcoat with SLC until mortar has reached sufficient compressive strength — check TDS.
Technical Properties
- Low-alkali formulation specifically designed for AAR (alkali-aggregate reaction) affected substrates
- EN 1504-3 structural grade — large-area application for extensive spall repairs on AAR-damaged structures
- Reduces risk of further AAR expansion in replacement repair mortar
- Low-shrinkage characteristic suited to large horizontal and vertical area repairs
Limitations
- Niche specification — appropriate only for confirmed or suspected AAR-affected structures; engineer must specify
- Not a direct substitute for Renderoc HB — performance and mix characteristics differ
- Higher cost than standard Renderoc grades; requires Fosroc specialist involvement to specify correctly
PROCUREMENT SOURCES
Mapei Planitop 400
polymer-modified rapid repair mortar for floors, 25 kg bag
System Description
Use for isolated floor depressions, damaged saw-cut edges, or localised substrate failure prior to self-levelling. Trafficable typically within 1–3 hours. Do not overcoat with SLC until mortar has reached sufficient compressive strength — check TDS.
Technical Properties
- Can be feathered to near-zero edge for localised transitions and surface irregularities
- Rapid-setting formulations allow same-day progression to self-levelling compound application
Limitations
- Not suitable for large-volume levelling — use self-levelling compound for areas exceeding 5 mm depth over large areas
- Requires surface priming — adhesion will fail on unprimed or contaminated substrates
PROCUREMENT SOURCES
System Description
Use for isolated floor depressions, damaged saw-cut edges, or localised substrate failure prior to self-levelling. Trafficable typically within 1–3 hours. Do not overcoat with SLC until mortar has reached sufficient compressive strength — check TDS.
Technical Properties
- Can be feathered to near-zero edge for localised transitions and surface irregularities
- Rapid-setting formulations allow same-day progression to self-levelling compound application
Limitations
- Not suitable for large-volume levelling — use self-levelling compound for areas exceeding 5 mm depth over large areas
- Requires surface priming — adhesion will fail on unprimed or contaminated substrates
PROCUREMENT SOURCES
Brand Equivalents
Side-by-side view of equivalent products across all major brands.
| Material | Ardex | Sika | Fosroc | Tremco / Other | Parchem / Mapei |
|---|---|---|---|---|---|
| Feather-edge skim patch compound | Ardex Feather Finish | Sika MonoTop-412N | Fosroc Renderoc FC | Parchem Renderoc FC | Mapei Planitop Fast 330 |
| Rapid-set floor patching mortar | Ardex RA 90 | Sika MonoTop-412N | Fosroc Renderoc LA | Parchem Speed Rep | Mapei Planitop 400 |
Disclaimer
Information is general only. Product selection must be confirmed against project requirements, substrate condition, exposure class, manufacturer technical data sheets, NCC requirements, Australian Standards (including AS 3600), and consultant or structural engineer specifications. Do not rely on this reference as a substitute for professional engineering advice.
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